He was the master of illusion and escape, but the greatest mystery of Harry Houdini's life may have been his end. On Halloween night, 1926, he staged the ultimate disappearing act.

Now, 81 years after a death that had been attributed variously at the time to peritonitis from a ruptured appendix, caused by a forceful blow to the stomach, or foul play, relatives of Houdini are pressing for the exhumation of his body to try to ascertain the causes of his death. Houdini is buried in Queens, New York.

The family will file a court petition on Monday seeking permission for the exhumation, lawyer Joseph Tacopina told reporters yesterday. "There was a motive to murder Harry Houdini and it was suppressed and covered up," he said.

Houdini's relatives, led by George Hardeen, a grandson of the illusionist's brother, Theodore, who was also a celebrated escape artist, have recruited prominent forensic pathologists to the investigation.

Investigators hope to examine Houdini's remains for traces of poison.

"It needs to be looked at," Mr Hardeen told the Associated Press. "His death shocked the entire nation, if not the world. Now, maybe it's time to take a second look."

Houdini was at the height of his powers when he died in Detroit at the age of 52. He had conquered Europe, dazzling audiences by making elephants appear to vanish from the stage of the London Hippodrome and freeing himself from the most elaborate restraints from Scotland to Russia. He was the highest paid Vaudeville entertainer in America.

After Houdini's body was brought by train to Manhattan's Grand Central station, more than 2,000 mourners attended his funeral. The US magicians' society honours him with an annual ceremony at his grave site to this day.

But the true story of Houdini's death proved even more elusive than the secret of his escapes. Within days of Houdini's demise, newspaper began speculating about murder. By that time Houdini was known as a sworn enemy of the Spiritualist movement, whose devotees promoted the idea of seances of communicating with the dead. Houdini took to infiltrating seances in disguise, or with policemen and reporters in tow, and came to devote a portion of his act to exposing such sessions as a fraud.

That war on self-styled psychics earned Houdini the lasting enmity of their followers, including Arthur Conan Doyle, the creator of Sherlock Holmes. In a new biography of the magician, authors William Kalush and Larry Sloman quote a letter from Doyle threatening revenge. "I think there is a general payday coming soon," Doyle is quoted as writing.

Two years later, Houdini was dead.

No autopsy was performed and the notorious feud with the Spiritiualists fuelled speculation that Houdini had died as a result of arsenic poisoning. Other suspicions have focused on a serum that he was administered in hospital.

If it were established that Houdini died of a result of a plot by such psychics that would further burnish his reputation, his followers believe.

At the time of his death, doctors diagnosed Houdini's last ailment as "traumatic appendicitis" following an encounter in Montreal a few days earlier in which he had invited two students to test his claim that he could sustain any blow to the abdomen. The two are believed to have hit Houdini repeatedly as he reclined on a sofa. However, that theory was later debunked by modern medicine.

In the latest quest for the truth, Mr Hardeen has been joined by a descendant of Houdini's fiercest enemy: a great granddaughter of a medium known as Margery. The illusionist had exposed her act, earning the wrath of Margery and her husband, Le Roi Crandon. In a 1924 seance, the medium is said to have conjured up a spirit that cursed Houdini.

"We need to use science to understand the world around us and to correct history," the medium's descendant, Anna Thurlow, told Newsday newspaper. "History might have had something wrong."

Life and times: Harry Houdini

Son of a rabbi, the performer known as Harry Houdini was born Ehrich Weiss in Hungary in 1874, and with his father emigrated to the US as a boy.

While still a child, he made his debut in show business as a circus trapeze artist, but later came under the spell of a French musician, Jean Eugene Robert-Houdin.

What began as a stage act based on traditional card tricks rapidly devolved into illusions and increasingly daring escapes.

As challenges paled, Houdini took to extricating himself from restraints inside locked boxes and under water in a crate in New York, or dangling high in the air - deriving excitement from the prospect that his failure could lead to imminent death.